Final Exam - Equine Orbit, Eyelids, & Lacrimal Glands

Question 1

what are some ways you can assess vision in a horse?

Answer 1

stationary object avoidance with a blindfold over the good eye

menace response

pupillary & dazzle response

Question 2

what is the number one test for assessing vision in a horse?

Answer 2

DAZZLE RESPONSE!!!!

Question 3

what are you looking for on ultrasound of an equine eye if you are concerned about vision or other issues?

Answer 3

looking at the pupil size & looking for retinal detachment

Question 4

if concerned about vision deficiencies in a horse, what should you do prior to sedation?

Answer 4

need to assess the reflexes

Question 5

what are clinical signs associated with orbital trauma in horses?

Answer 5

asymmetry of periocular structures, prominent 3rd eyelid, epiphora, emphysema, & unilaterally reduced airflow

Question 6

_____ & ______ are more susceptible to traumatic fracture of the bony orbit

Answer 6

horses & cattle

Question 7

how is orbital trauma diagnosed?

Answer 7

complete physical, neurologic exam, & ophthalmic exam - rads, ultrasound, & CT/MRI

Question 8

what treatment is indicated for orbital trauma? what affects prognosis?

Answer 8

conservative medical management if non-displaced

surgical correction

prognosis depends on severity of trauma!

Question 9

where do eyelid lacerations most commonly occur in horses?

Answer 9

lateral to medial tear is most common - upper lid is most likely

Question 10

what is the required treatment for eyelid laceration? why?

Answer 10

surgical repair - essential to avoid exposure & development of keratitis

Question 11

what is the essential treatment indicated for periocular squamous cell carcinomas?

Answer 11

debulking is essential followed by cryotherapy, hyperthermia, chemo, piroxicam, or photodynamic dye therapy

Question 12

when do we see periocular habronemas in horses?

Answer 12

occurs in the humid summer months

Question 13

what is the vector of habronemiasis? what is the pathophysiology of it?

Answer 13

horse & stable flies

adult habronema live in the equine stomach & larvae in feces are picked up by fly larvae

infective habronema larvae are deposited near mucocutaneous junctions or on skin wounds caused by adult flies

Question 14

what treatment is used for ocular habronemiasis in horses?

Answer 14

topical insecticide ointment, fly control, systemic ivermectin, & anti-inflammatories (nsaids or steroids)

Question 15

what is the most common ocular abnormality recognized in foals? why?

Answer 15

entropion - due to loss of periorbital fat or dehydration

Question 16

how is entropion corrected in foals?

Answer 16

temporary stay sutures

wedge technique used for permanent correction

temporary injectable

Question 17

where are the most common locations for ocular squamous cell carcinomas in horses?

Answer 17

scleral, corneal, or both

Question 18

what is the ideal treatment used for equine ocular squamous cell carcinomas? why? how is it used & what are the risks?

Answer 18

debulking + strontium-90 irradiation is ideal

it doesn’t harm inner structures of the globe & no residual radiation is left

need 1-3 applications at 30 day intervals

risks - can cause ulcers to heal slowly

Question 19

what medical treatment is used for periocular sarcoids in horses?

Answer 19

chemotherapy - 5-F cisplatin

immunotherapy

irritants to cause immune reaction

Question 20

what are your treatment options for equine periocular sarcoids?

Answer 20

medical

surgical excision

cryotherapy

radiation - iridium implants

mitomycin C & acyclovir

Question 21

what is exophthalmos?

Answer 21

normal sized globe is pushed out by periocular tissues that can lead to exposure keratopathies

Question 22

what are the main causes of exophthalmos in horses?

Answer 22

inflammation/cellulitis

neoplasia

cystic mass

Question 23

T/F: blockage of the nasolacrimal duct will result in epiphora

Answer 23

true

Question 24

what is different about the nasolacrimal ducts in donkeys when compared to horses?

Answer 24

in donkeys, they are located on the lateral aspect!!! not medial!!!

Question 25

how can you check the patency of the nasolacrimal duct in a horse?

Answer 25

patency test - fluorescein stain

Question 26

what should you do for a horse that has a congenital lack of opening in their nasolacrimal duct?

Answer 26

create a stoma

Question 27

what does the menace response test?

Answer 27

tests the retina, CN II, & CN VII

don’t brush the lashes & don’t brush with air

Question 28

what does the PLR test?

Answer 28

direct & indirect responses

tests the retina, CN II, midbrain, & CN III

Question 29

what does the dazzle reflex test?

Answer 29

tests the retina, CN II, & CN VII

photophobic effect

Question 30

what nerve blocks should be done prior to an ophthalmic exam in a horse?

Answer 30

auriculopalpebral branch of the facial nerve (CN VII) for motor block

frontal branch of the trigeminal nerve (CN V) for sensation block

Question 31

why are horses & cattle more susceptible to fractures of the orbit?

Answer 31

they have a full/complete bony orbit - more susceptible to traumatic fractures of the arch

Question 32

where is the proximal & distal location of the nasolacrimal ducts in horses?

Answer 32

proximal - medial canthus

distal - rostral nostril